monotreme

mon·o·treme

(mŏn′ə-trēm′)

n.

Any of various egg-laying mammals of the order Monotremata of Australia and New Guinea, whose only living members are the platypus and the echidnas.

[From New Latin Monotrēmata, order name : mono- + Greek trēma, trēmat-, perforation (from the fact that they have a single cloaca rather than an anus separate from genital and urinary orifices, as in placental mammals and marsupials); see terə- in Indo-European roots.]

mon′o·trem′a·tous(-trĕm′ə-təs) adj.

monotreme

(ˈmɒnəʊˌtriːm)

n

(Animals) any mammal of the primitive order Monotremata, of Australia and New Guinea: egg-laying toothless animals with a single opening (cloaca) for the passage of eggs or sperm, faeces, and urine. The group contains only the echidnas and the platypus

[C19: via New Latin from mono- + Greek trēma hole]

monotrematousadj

mon•o•treme

(ˈmɒn əˌtrim)

n.

any egg-laying mammal of the order Monotremata, comprising only the duckbill and the echidnas of Australia and New Guinea.

mon·o·treme

(mŏn′ə-trēm′)

The most primitive type of living mammal. Monotremes lay eggs, and the females have no teats but provide milk directly through the skin to their young. Monotremes include only the duck-billed platypus, found in Australia and New Guinea, and the echidnas, found only in New Guinea.

In addition to its obvious physical characteristics--such as webbed feet, rubbery snout, and ears at the jaw's base--the platypus is a venomous monotreme with electroreception, double cones in its eyes, a jaw unique to mammals, and bones in its pectoral girdle that other mammals lack (see Grant 2008).

At present, sequencing of the whole genome of more than 100 mammalian species, including marsupial and monotreme species is available as well as that of many other vertebrate species including reptiles, birds and fish.

As a biological side note, the term monotreme does not specifically mean that the animal is an egg-laying mammal; rather it refers to the fact that these creatures have a single opening for the passage of eggs or sperm, faeces and urine.

An egg-laying monotreme (a distinction is shares with the echidna), the platypus is found in the fresh water lakes and streams of eastern Australia where it forages for prey with a highly sensitive bird-like bill.

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